From 97638ba32447a5184b3bd0a48fe1a678c334648e Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sun, 26 May 2019 18:39:20 +0100
Subject: Add MemStream

A wrapper around open_memstream
---
 libadhocutil/memstream.cpp               | 51 ++++++++++++++++++++++++++++++++
 libadhocutil/memstream.h                 | 36 ++++++++++++++++++++++
 libadhocutil/unittests/Jamfile.jam       |  8 +++++
 libadhocutil/unittests/testMemStream.cpp | 34 +++++++++++++++++++++
 4 files changed, 129 insertions(+)
 create mode 100644 libadhocutil/memstream.cpp
 create mode 100644 libadhocutil/memstream.h
 create mode 100644 libadhocutil/unittests/testMemStream.cpp

diff --git a/libadhocutil/memstream.cpp b/libadhocutil/memstream.cpp
new file mode 100644
index 0000000..35d42ad
--- /dev/null
+++ b/libadhocutil/memstream.cpp
@@ -0,0 +1,51 @@
+#include "memstream.h"
+#include <cstdlib>
+
+namespace AdHoc {
+	MemStream::MemStream() :
+		buf(nullptr),
+		len(0),
+		strm(open_memstream(&buf, &len))
+	{
+	}
+
+	MemStream::~MemStream()
+	{
+		fclose(strm);
+		free(buf);
+	}
+
+	MemStream::operator FILE * ()
+	{
+		return strm;
+	}
+
+	MemStream::operator const char * () const
+	{
+		fflush(strm);
+		return buf;
+	}
+
+	MemStream::operator std::string_view() const
+	{
+		fflush(strm);
+		return { buf, len };
+	}
+
+	const char * MemStream::buffer() const
+	{
+		return *this;
+	}
+
+	std::string_view MemStream::sv() const
+	{
+		return *this;
+	}
+
+	size_t MemStream::length() const
+	{
+		fflush(strm);
+		return len;
+	}
+}
+
diff --git a/libadhocutil/memstream.h b/libadhocutil/memstream.h
new file mode 100644
index 0000000..b807d8b
--- /dev/null
+++ b/libadhocutil/memstream.h
@@ -0,0 +1,36 @@
+#ifndef LIBADHOC_MEMSTREAM_H
+#define LIBADHOC_MEMSTREAM_H
+
+#include <visibility.h>
+#include <cstdio>
+#include <string_view>
+
+namespace AdHoc {
+	class DLL_PUBLIC MemStream {
+		public:
+			MemStream();
+			~MemStream();
+
+			MemStream(const MemStream &) = delete;
+			MemStream(MemStream &&) = delete;
+
+			void operator=(const MemStream &) = delete;
+			void operator=(MemStream &&) = delete;
+
+			operator FILE * ();
+			operator const char * () const;
+			operator std::string_view () const;
+
+			const char * buffer() const;
+			std::string_view sv() const;
+			size_t length() const;
+
+		private:
+			char * buf;
+			size_t len;
+			FILE * strm;
+	};
+}
+
+#endif
+
diff --git a/libadhocutil/unittests/Jamfile.jam b/libadhocutil/unittests/Jamfile.jam
index 6b04540..0b749a8 100644
--- a/libadhocutil/unittests/Jamfile.jam
+++ b/libadhocutil/unittests/Jamfile.jam
@@ -287,3 +287,11 @@ run
 	<library>boost_utf
 	;
 
+run
+	testMemStream.cpp
+	: : :
+	<define>BOOST_TEST_DYN_LINK
+	<library>..//adhocutil
+	<library>boost_utf
+	;
+
diff --git a/libadhocutil/unittests/testMemStream.cpp b/libadhocutil/unittests/testMemStream.cpp
new file mode 100644
index 0000000..b244b5e
--- /dev/null
+++ b/libadhocutil/unittests/testMemStream.cpp
@@ -0,0 +1,34 @@
+#define BOOST_TEST_MODULE NvpParse
+#include <boost/test/unit_test.hpp>
+#include <boost/mpl/list.hpp>
+
+#include "memstream.h"
+
+using namespace AdHoc;
+
+BOOST_FIXTURE_TEST_SUITE(s, MemStream);
+
+BOOST_AUTO_TEST_CASE(empty)
+{
+	BOOST_CHECK_EQUAL("", this->sv());
+	BOOST_CHECK_EQUAL("", this->buffer());
+	BOOST_CHECK_EQUAL(0, this->sv().length());
+	BOOST_CHECK_EQUAL(0, this->length());
+}
+
+using cast_types = boost::mpl::list<const char *, std::string_view, FILE *>;
+BOOST_AUTO_TEST_CASE_TEMPLATE(casts, T, cast_types )
+{
+	auto dummy = [](const T &) { };
+	dummy(*this);
+}
+
+BOOST_AUTO_TEST_CASE(simple)
+{
+	auto len = fprintf(*this, "Some %s write.", "simple");
+	BOOST_CHECK_EQUAL("Some simple write.", this->buffer());
+	BOOST_CHECK_EQUAL(len, this->length());
+}
+
+BOOST_AUTO_TEST_SUITE_END();
+
-- 
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